Steam heaters in homes often make noise because condensed steam is trapped in the pipes. As the steam runs through the system, it pushes the water through. When this water hits an elbow, valve or other fitting, a banging or knocking sound is heard.
Most of the time, a homeowner can stop the sounds from the steam heater by maneuvering the radiator so that it is tipped toward the boiler. This way, water is unable to settle into the system.
If a steam heater is squeaking or making a whistling sound, the air vent needs to be replaced. This vent is attached to the pipe near the bottom of the heater. Replacement air vents are available at most plumbing supply stores, and are easy to install.
To fix the whistling from a faulty air vent, the steam heater must be turned off, and the old vent must be removed by twisting. When the old vent is removed, the new vent must be threaded into the heater. The valve then needs to be adjusted, and the handle of the valve should be put back in place. The steam heater can be turned back on at this point, but it may need a few minutes to fill. Owners should check for leaks after changing the filter and turning the heater on.